Ion pumps and passive cotransport systems are present in the membrane of practically all animal cells, to maintain cellular ionic composition, to transport electrolytes and fluid across epithelia, and to maintain an osmotic balance and regulate volume of the cells. Furthermore, ion pumps in cell membranes of the cornea and lens have a crucial role in maintaining the transparency of these tissues. The anatomical and functional integrity of the endothelium is critical for maintaining the transparency of the cornea. However, medical management of cell loss and physiological function is liimited. Thus, research to develop methods to enhance fluid transport is highly relevant. Cataract is a prevalent health problem for which there is no medical treatment. Many mechanisms contribute to the maintenance of lens transparency. In recent years it has become clear that among many unknown factors, osmotic equilibrium, Na:K ATPase activity and normal GSH levels are necessary to maintain lens transparency. The aim is to further characterize: mechanisms of ion transport, fluid transport, membrane permeability, transport ATPases, metabolic activity and related physiological parameters important for the maintenance of the transparency of the cornea and lens. To this aim, we will use electrophysiological, biochemical and spectrofluorometric techniques. Data will be analyzed using conventional electrical modelling as well as the formalism of irreversible thermodynamics. We expect to provide models of ion and fluid movement across the corneal epithelium, corneal endothelium and lens membranes.